[VOL-4290] Voltha go library updates for gRPC migration

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/github.com/coreos/bbolt/go.mod b/vendor/github.com/coreos/bbolt/go.mod
new file mode 100644
index 0000000..c2366da
--- /dev/null
+++ b/vendor/github.com/coreos/bbolt/go.mod
@@ -0,0 +1,5 @@
+module go.etcd.io/bbolt
+
+go 1.12
+
+require golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5